JPH08209348A - Production of substrate for damond coated tool - Google Patents

Abstract

PURPOSE: To produce a cemented carbide substrate having high adhesion between coating diamond when a diamond coating film is formed on a cemented carbide substrate by a vapor phase synthesis method so as to produce a diamond coated tool. CONSTITUTION: A cemented carbide substrate is heated at above the temp. at which diamond is formed by a vapor phase method in a non-oxidizing atmosphere to vaporize and disperse volatile impurities and low m.p. substances in the substrate and to form a soluble deposit from the substrate on the substrate and then the deposit is removed from the substrate. A diamond coated tool whose diamond is less liable to peel is obtd. using the resultant substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cemented carbide substrate for producing a diamond-coated tool by coating a cemented carbide substrate with diamond by a vapor phase synthesis method, and more particularly to a method for producing a cemented carbide substrate A method of manufacturing a tall substrate.

[0002]

2. Description of the Related Art Conventionally, ultrahigh pressure has been applied to diamond tools.
Sintered diamond obtained by sintering diamond grains produced at high temperature with a binder or natural diamond has been used. On the other hand, a diamond vapor phase synthesis technology that decomposes hydrocarbons and synthesizes and coats diamond on the surface of the substrate has been developed, and the cost is low, and coating that corresponds to the shape of the substrate is possible and there is high flexibility. It's getting a lot of attention. In particular, it is expected that if the surface of cemented carbide, which is widely used as a tool at present, can be coated with good adhesion, excellent properties can be obtained in turning, milling, end milling and the like.

Many surface treatment methods have been proposed in order to coat a diamond film on the surface of a cemented carbide with good adhesion. For example, JP-A-3-107460 and JP-A-3-1837.
Japanese Unexamined Patent Publication No. 74-74 discloses a method of forming innumerable protrusions on the surface of a substrate to increase the degree of adhesion by the anchor effect.
Japanese Patent Publication No. 096 (Registered 1458291) discloses a method in which sharp nuclei are formed on the surface of the substrate to uniformly generate nuclei of diamond and increase the adhesion. These methods increase the adhesion to diamond by roughening the surface of the cemented carbide substrate.

Further, the method disclosed in Japanese Patent Application Laid-Open No. 61-523683 (Registration 1472889) is different from the above-mentioned method except that the substance contained in the surface portion of the cemented carbide has a bad influence on the precipitation of diamond. There is. The cemented carbide contains, for example, tungsten carbide as a main component, and carbide powder such as titanium and tantalum is used.
Etc. are arranged and compression-sintered. In such a cemented carbide, for example, cobalt has a bad influence particularly on the diamond coating formation. Therefore, if this is removed before the diamond coating formation, the influence of the substance is eliminated.

Regarding the removal of substances that have an adverse effect on diamond formation, the wet etching treatment using acid or alkali is shown in the above-mentioned reference, but in such a treatment method, the etching is performed on the cemented carbide. There is a risk that the substrate will extend to the inside and that the undissolved residue will adhere to the substrate surface. Dry etching using plasma or the like is also conceivable, but this method has problems that the equipment is complicated, the processing takes time, and only the outermost surface can be processed. In addition to the binder phase, the cemented carbide also contains additives and impurities that adversely affect the deposition of vapor phase diamond. And the crystal growth of diamond is impaired and the crystallinity is lowered, or the presence of a deposition portion at the interface between the diamond film and the substrate reduces the adhesion. It is difficult to remove this material efficiently with the etching processes disclosed to date.
Therefore, practically, it is desired to develop a method that solves these problems.

[0006]

Among the above-mentioned known techniques, in particular, the removal of substances contained in cemented carbides, which have an adverse effect on the formation of diamond coating, has been studied for the purpose of developing a method without the drawbacks of the above-mentioned known methods. As a result, the present invention has been completed.

[0007]

In order to achieve the above object, the present inventor has found that an additive which adversely affects the precipitation of diamond,
It was found that impurities and the like have high volatility at the substrate temperature at the time of diamond film formation and have a lower melting point than the substrate temperature, and an efficient removal method of those substances was examined. As a result, the cemented carbide substrate is heated in a non-oxidizing atmosphere at a temperature above the vapor phase diamond formation temperature to volatilize volatile impurities and low melting point substances in the substrate, and the remaining low melting point substances are deposited on the substrate. After forming the deposit, the deposit was removed from the substrate to complete a method for producing a diamond-coated tool substrate.

Impurities, volatilization and deposition of low-melting point substances due to heating of the cemented carbide substrate occur at 700 ° C. or higher. However, to obtain a diamond film-forming substrate thereafter, the substrate temperature is the same as that at the time of diamond synthesis. It is preferable to heat above. Generally, the higher the heating temperature is, the more volatilized impurities,
The precipitation occurs efficiently, but on the other hand, the toughness of the cemented carbide decreases. The upper limit of the heating temperature depends on the type of cemented carbide, but in the case of WC-Co system, 1200 ° C, WC-TaC-Co
Systems, WC-TiC-Co systems and WC-TiC-Ta (N
b) In the case of C-Co system, if the temperature is heated to 1300 ° C or higher, the toughness of the cemented carbide substrate decreases due to the dissolution of the bonding layer. On the contrary, when the temperature is lower than the substrate temperature during synthesis, the vaporization and deposition of impurities are insufficient, and the vaporization of impurities during deposition and the deposition on the substrate surface inhibits the crystal growth and the adhesion and crystallinity of the film are reduced. descend. Therefore, the heating temperature is practically 700 ° C to 1300 ° C.
And the substrate temperature at the time of synthesizing the diamond film or higher. Further, the heating time is sufficient if it affects the surface layer of the substrate (in the range of 1 to 30 μm from the surface that affects the film formation of diamond), so that about 0.1 to 2 hours is sufficient.
In addition, the atmosphere during heating of the cemented carbide substrate in the present invention is preferably non-oxidizing, and is preferably hydrogen, vacuum, or an inert gas.

In order to remove the substance deposited on the surface of the cemented carbide substrate, polishing with abrasive grains, use of abrasive grains ultrasonically vibrated in a solution, chemical and electrochemical etching treatment,
It is effective to apply a plasma etching process or the like.
Abrasive grains used for removal are diamond, silicon carbide, alumina, boron nitride, boron carbide, etc., having a particle size of 1 to 50 μm.
m is suitable. An aqueous solution of hydrochloric acid, nitric acid, sulfuric acid or the like is used for the chemical etching treatment, an aqueous solution of hydrochloric acid, nitric acid, sulfuric acid, sodium hydroxide, potassium hydroxide or the like is used for the electrochemical etching treatment, and hydrogen is used for the plasma etching.
Nitrogen, oxygen, helium, argon ions or the like can be used. It is important to remove only the substance deposited on the surface of the cemented carbide in the treatment using these abrasives and chemicals.
If it is excessively performed, the surface of the cemented carbide from which impurities and the like are removed is scraped off in the present invention, and the adhesion is deteriorated due to deterioration of the cemented carbide substrate. In addition, if a protrusion group is formed on the surface of the cemented carbide by removing the residue by electrolytic polishing and alkaline cleaning in advance, the adhesion of the formed diamond film to the substrate is further increased.

[0010]

EFFECTS OF THE INVENTION It has become possible to provide a substrate having a high adhesive force for diamond coating, as compared with the conventionally manufactured cemented carbide substrate for a diamond coated tool. That is, it becomes possible to provide a diamond tool in which diamond is not easily peeled off, and its practical value is extremely high.

Next, the present invention will be explained with reference to Examples and Comparative Examples. Example 1 6% by weight of a substrate, Co, WC and inevitable impurities and additives (polymer compound, free carbon, Cu, Al, S)
Cemented carbide milling tip (SEE) made of n, Pb, etc.
N1203) was heated in hydrogen at 100 Torr and 1000 ° C. for 1 hour. By this heating, the low melting point substance and the volatile impurities were volatilized, and the deposit was formed on the chip surface.
The surface of this substrate after cooling was polished with SiC having an average particle diameter of 5 μm for about 2 minutes (paste-like material in which SiC particles were dispersed was rubbed with a polishing cloth and then washed with ethanol). . By this polishing, the deposits on the surface were removed. Next, in order to evenly generate diamond nuclei, a scratching treatment is performed with a 0.25 μm diamond paste for about 1 minute. Specifically, diamond particles are dispersed into a paste shape and rubbed with a polishing cloth by hand. And then washed with ethanol. A diamond film having a thickness of 8 μm was formed on the surface of the substrate by the hot filament CVD method (deposition conditions for the diamond film: source gas is hydrogen 100 SCC
M, methane 1 SCCM, reaction pressure 100 Torr, filament temperature 2100 ° C., substrate temperature 800 ° C., substrate-filament distance 8 mm, synthesis time 3 hours).

The produced diamond-coated chip was 50 mm × 5 by using a 50 mm × 50 mm × 300 mm aluminum die cast block (ADC12) as a work material.
The milling evaluation was performed by cutting the end surface of 0 mm. The evaluation was made by attaching one chip to the face mill and how many times the end face of the aluminum die cast block could be cut. The chip life was judged at the time of peeling the diamond film. The cutting conditions were a depth of cut of 0.5 mm, a feed rate of 0.05 mm / blade, and a cutting rate of 1000 m / min. The evaluation was carried out under the above conditions, and when observed every 10 cuttings, the diamond film was peeled off after 1670 cuttings.

Example 2 A cemented carbide milling chip having the same composition as in Example 1 was used in Example 1.
Heat treatment was performed in the same manner as in Example 1 to obtain a chip having a deposit on the same surface as in Example 1. After cooling, the chip was immersed in a 7% nitric acid solution for 3 minutes to remove only the substance deposited on the surface. After that, the scratching treatment was performed in the same manner as in Example 1. When this chip was used as a substrate and a diamond film was coated under the same conditions as in Example 1 and a milling evaluation was performed, the diamond film was peeled off after 1520 cuttings. Example 3 A cemented carbide milling chip having the same composition as in Example 1 was treated in the same manner as in Example 1 except that the heating temperature was 800 ° C. to obtain a chip having a deposit on the surface. After cooling, the molten deposits were removed and the scratch treatment was performed under the same conditions as in Example 1.
When the diamond film was coated and milled under the same conditions as above, the diamond film was peeled off after cutting 1230 times.

Example 4 A cemented carbide milling chip having the same composition as in Example 1 was heat-treated in the same manner as in Example 1 to obtain a chip having a deposit on the same surface as in Example 1. After cooling this chip 200c
It was immersed in a liquid containing 100 g of 20 μm SiC particles in water of c, and ultrasonic waves of 150 W were applied for 20 minutes to remove only the substance that was deposited on the surface of the cemented carbide chip. Then Example 1
The scratching process was performed in the same manner as in. This substrate was used in Example 1.
When the diamond film was coated and milled under the same conditions as above, the diamond film was peeled off after cutting 1310 times.

Example 5 The same cemented carbide chip as in Example 1 was subjected to electrolytic polishing using a pulse voltage in advance. The treatment conditions are 10% hydrochloric acid solution in electrolyte, chip 5 as an anode, voltage 5V, current 1A, pulse frequency 1/4 Hz, pulse width 100 msec, polishing time 4 minutes, and the residue adhered to the surface is 10% KOH. It was immersed in an aqueous solution for 10 minutes to be dissolved, and a projection group having a height of about 6 μm was formed on the surface. This chip was subjected to heat treatment under the same conditions as in Example 1, removal of only the substance deposited on the surface of the cemented carbide chip, and scratch treatment. When this chip was coated with a diamond film under the same conditions as in Example 1 and a milling evaluation was carried out, the diamond film was peeled off after cutting 2360 times. Example 6 A diamond-coated chip was prepared in exactly the same manner as in Example 5, except that a cemented carbide milling chip (SEEN1203) containing 10% by weight of TaC, 6% by weight of Co, WC, and inevitable impurities and additives was used as the substrate. When this chip was evaluated under the same conditions as in Example 1, the diamond film peeled off after cutting 2150 times.

Comparative Example 1 A diamond-coated (thickness: 8 μm) substrate was obtained in the same manner as in Example 1 except that the heat treatment of the chip and the removal of the deposit were not performed. When the milling evaluation was performed in the same manner as in Example 1, the diamond film was peeled off after cutting 10 times. Since the substance contained in the cemented carbide chip has a bad influence on the precipitation of diamond, sufficient adhesion of the diamond film to the substrate could not be obtained and the diamond film was peeled off almost at the same time as the start of cutting.

Comparative Example 2 Heat treatment was carried out using the same cemented carbide chip as in Example 1. The heat treatment temperature was 650 ° C., and the other conditions were the same as in Example 1. After cooling, the deposited material was removed and scratched under the same conditions as in Example 2, the diamond film was coated under the same conditions as in Example 1, and milling evaluation was performed.
The diamond film peeled off after 10 times. This is because the heat treatment temperature is lower than the substrate temperature, and the volatilization and deposition of substances that adversely affect the deposition of diamond were insufficient and the adhesion could not be improved.

Claims (7)

[Claims] 1. A cemented carbide substrate is heated in a non-oxidizing atmosphere at or above a vapor deposition diamond formation temperature to volatilize volatile impurities and low melting point substances in the surface layer of the substrate, and A method for producing a substrate for a diamond-coated tool by producing a deposit and then removing the deposit from the substrate. 2. The method for producing a substrate for a diamond-coated tool according to claim 1, wherein the cemented carbide substrate has a group of protrusions formed on its surface by electrolytic polishing. 3. The method for producing a diamond-coated tool substrate according to claim 2, wherein the electrolytic polishing is performed in a mineral acid. 4. The method for producing a diamond-coated tool substrate according to claim 2, wherein the electrolytic polishing is performed by a pulse voltage. 5. The method for producing a substrate for a diamond-coated tool according to claim 1, wherein the deposits formed on the substrate are removed by polishing with abrasive grains. 6. The diamond-coated tool according to claim 1, wherein the deposit is removed by placing a cemented carbide substrate capable of forming the deposit in a solution containing abrasive grains and ultrasonically vibrating the abrasive grains. Of manufacturing a substrate for use. 7. The method for producing a diamond-coated tool substrate according to claim 1, wherein the removal of the molten precipitate is performed by etching.